1. Field of the Invention
The invention relates to a concrete paving machine. More specifically, the invention relates to a zero clearance, variable width paving machine which allows laying a paving bed beyond the tracks of the paving machine up to a curb or other vertical surface. Paving of this nature can be accomplished from one or both sides of the current invention paving machine. The paving pan is located behind the tractor and can be expanded to or past the dimension of the paver tracks. Thus, the current paving machine provides zero clearance paving which negates completion of a paving job with a subsequent pass to cover the area occupied by the tracks as is the case with prior art paving machines. Using the same paving pan, the machine can also provide variable width conventional paving.
Slip form pavers have been widely used to pave concrete surfaces, and in general comprise a tractor unit supported on track assemblies with a propulsion means, steering means and elevational control. Using this tractor for conventional paving, a paving pan is located near the mid-point of the tractor, consisting of a spreading auger, vibration means for consolidation of the concrete, and a screed. On each side of the paving pan inside of the traction means are the lateral forms which create the side edges of the concrete slab formed on the roadway as the machine moves forward.
In general, when applying a concrete slab to a road surface using the above described slip form paver, the road surface must be of sufficient width to accommodate the slab and a track path on each side of the slab for track travel. The width of a particular track path generally is equal to that portion of the outboard track extending the greatest distance beyond the respective concrete slab side forms. The dimension between the outer edge of the track path and the respective outer edge of the concrete slab applied is the offset or clearance requirement of the paver. In the current invention, this dimension can be zero, and hence the term xe2x80x9czero clearancexe2x80x9d paving.
In many cases a vertical abutment such as a curb or highway center median may border the road surface such that the outboard tracks cannot travel upon or straddle the raised structure. In these instances heretofore, a number of varied complicated procedures had to be followed to complete the paving operation. However, the method and apparatus of the current invention provides an improved paving apparatus capable of simultaneously applying a concrete slab of varying width over the surface to be paved and directly against a vertical abutment located on either or both sides of the machine, negating complicated finishing procedures.
2. Prior Art
The prior art does not disclose a concrete paver which can pave at zero clearance from either or both sides of the machine concrete slabs of varying dimensional width.
Now referencing the prior art patents, U.S. Pat. No. 4,900,186 to Swisher et al teaches a method and apparatus of providing a paving apparatus capable of simultaneously applying a concrete slab of substantial width over the surface to be paved and directly against a vertical abutment. This prior art machine, however, paves against a vertical abutment on only one side, in contrast to the current invention, which can do this on either side.
Also, in U.S. Pat. No. 3,992,124 to Schrader, the art teaches a device for adjusting the working width of a road finisher comprising a main support beam adapted to be carried by the road finisher located behind the machine for finishing the road surface. The width of the device is variable and, therefore, could be used to finish concrete exterior to an area between the tracks of the vehicle and a curb. However, the invention does not teach the use of available width distribution means, which contrasts this patent from the current invention.
U.S. Pat. No. 4,988,233 to Kaslev et al teaches a method and apparatus of providing a paving apparatus capable of simultaneously applying a concrete slab of substantial width over the surface to be paved and directly against a vertical abutment. It may be paved against a vertical abutment from either side. This prior art machine can only pave a fixed width, whereas the current invention can pave a variable width slab of up to several lanes at one time.
The invention teaches a slip form paving machine which can be used for both zero clearance variable width and variable width conventional paving. The main frame of the machine is designed to hydraulically extend to varying desired widths. The paving assembly, attached to the main tractor assembly frame, can be contemporaneously adjusted as wide as the main frame of the machine or further past the exterior limits for additional clearances, if required. The paving pan, part of the pan assembly, also can be extended to conform to these various widths. In a xe2x80x9czero clearancexe2x80x9d paving mode, the pan is located behind the main tractor frame, whereas in conventional paving, the same pan is located under the center of the main frame inside of the tracks. The current invention can zero clearance pave from either side or both. In addition, the paving pan can be adjusted to pave varying surface angles, if required.
The foregoing and additional advantages and characterizing features of the present invention will become clearly apparent upon reading of the following detailed description together with the included drawings.